Renal handling of cathodic trypsin-like immunoreactivity in man

The renal handling of cathodic trypsin-like immunoreactivity (TLI) was examined in 60 healthy persons (group I), 59 patients with proteinuria (group II), 7 healthy men receiving intravenous lysine to partially inhibit renal tubular protein reabsorption (group III) and 20 patients who underwent diagnostic renal vein catheterization (group IV). The urinary TLI concentration and TLI ratio (TLI clearance divided with creatinine clearance) were higher in group II than group I (p less than 0.001, Mann-Whitney test). In group II negative correlations were present between serum TLI and creatinine clearance (Spearman's rho = -0.84, p less than 0.001) and between TLI ratio and creatinine clearance (rho = -0.76, p less than 0.001). In group III the renal TLI clearance was undetectable before lysine but increased to a maximal median value of 4.00 ml/min per 1.73 m2 (range: 2.44-9.25 ml/min per 1.73 m2) after lysine. In group IV, the renal arterio-venous extraction of TLI was correlated to inulin extraction (rho = 0.85, p less than 0.001). The glomerular filtrability (the ratio between TLI and inulin extractions) was median 0.53 (range: 0.13-0.94). In conclusion, TLI has a high glomerular filtration and an almost complete tubular reabsorption and catabolism (with normal kidney function).